“…The bubble sizes in the bubble column were also measured by the dual conductivity probe technique along with the ultrasonic measurements in separate experiments . The Sauter mean diameter is about 0.6 cm when the column is operated in the homogeneous flow regime.…”
Section: Resultsmentioning
confidence: 99%
“…More recently, Soong et al has applied the ultrasonic technique to characterize slurries in a system consisting of molten paraffin wax, nitrogen, and glass beads at 189 °C. Furthermore, the application of the measurement of ultrasound transmission for gas holdup − and for gas holdup as well as the low concentration of solid (up to 1 wt %) under limited superficial gas velocities (up to 3 cm/s) in a slurry bubble-column reactor has been reported. , This leads to the initial study of using the ultrasonic technique for the measurement of solid holdup in a three-phase gas−liquid−solid bubble-column reactor over a wide range of superficial gas velocities and solid holdup and ultimately exploring this technique in a three-phase bubble-column reactor at elevated temperatures and pressures. 1 Effect of solids on the ultrasonic signal.…”
An indirect method (ultrasonic) and a direct technique were used to measure solid holdup in a
bubble-column reactor. Nitrogen, water, and fine glass beads were used as the gas, liquid, and
solid phases, respectively. The solid particle concentration in the slurry was varied from 5 to 30
wt %, and the gas superficial velocity was increased from 0.5 to 12 cm/s. The solid holdup
measurements by the ultrasonic technique compared reasonably well with results obtained by
the direct sampling technique.
“…The bubble sizes in the bubble column were also measured by the dual conductivity probe technique along with the ultrasonic measurements in separate experiments . The Sauter mean diameter is about 0.6 cm when the column is operated in the homogeneous flow regime.…”
Section: Resultsmentioning
confidence: 99%
“…More recently, Soong et al has applied the ultrasonic technique to characterize slurries in a system consisting of molten paraffin wax, nitrogen, and glass beads at 189 °C. Furthermore, the application of the measurement of ultrasound transmission for gas holdup − and for gas holdup as well as the low concentration of solid (up to 1 wt %) under limited superficial gas velocities (up to 3 cm/s) in a slurry bubble-column reactor has been reported. , This leads to the initial study of using the ultrasonic technique for the measurement of solid holdup in a three-phase gas−liquid−solid bubble-column reactor over a wide range of superficial gas velocities and solid holdup and ultimately exploring this technique in a three-phase bubble-column reactor at elevated temperatures and pressures. 1 Effect of solids on the ultrasonic signal.…”
An indirect method (ultrasonic) and a direct technique were used to measure solid holdup in a
bubble-column reactor. Nitrogen, water, and fine glass beads were used as the gas, liquid, and
solid phases, respectively. The solid particle concentration in the slurry was varied from 5 to 30
wt %, and the gas superficial velocity was increased from 0.5 to 12 cm/s. The solid holdup
measurements by the ultrasonic technique compared reasonably well with results obtained by
the direct sampling technique.
“…The detailed information of the bubble-column-reactor in which the ultrasonic investigation was conducted has been reported elsewhere [10,13]. The transparent acrylic bubblecolumn-reactor has an internal diameter of 8.89 cm and a height of 290 cm (Fig.…”
For the optimum design and operation of gas‐liquid‐solid three‐phase reactors, the degree of dispersion of the solid (catalyst) in the reactor must be measured, understood, and controlled. Accurate means of diagnosing the solids holdup are needed. An ultrasonic transmission technique has been developed to measure this parameter in a gas‐liquid‐solid bubble column reactor. The results presented in this study show that the transit time of an ultrasonic signal is influenced by the variation of solids holdup and the operating conditions in the bubble column.
“…In this work, we report for the first time, an ultrasound-based technique to determine mixing time in an unbaffled vortex mixer incorporating a magnetic needle coupled to an external magnetic drive. Ultrasound technique (UT) has been widely used in process applications spanning a wide range of applications like determination of bubble size and density in bubble columns, , liquid hold up in solvent extraction contactors, , estimation of solid concentration in stirred tanks, estimation of liquid levels in a multiphase system, − estimation of solution concentrations, and determination of physical properties of fluids , to name a few. In a few manifestations, UT has been used to determine residence time distribution in the flow of polymer melt through an extruder. , However, to the best of our knowledge, there has been no report on application of UT in determining mixing time in vortex reactors.…”
A vortex reactor represents an important class of equipment
in
chemical processing industries pertaining to crystallization and precipitation.
They are characterized by the presence of a vortex generated due to
rotation of a centrally placed impeller/magnetic needle at its center.
The addition of reactants into the vortex leads to their mixing under
forced vortex conditions. Estimation of mixing time in such reactors
is essential for the proper design of reactors. In this work, we
propose a novel technique to estimate the mixing time in a vortex
reactor using an ultrasonic technique. As tracer is injected into
the bulk liquid being stirred, there is a change in the speed of
sound of the liquid in the vessel. This dynamic variation of sound
velocity is acquired and analyzed to determine mixing time as well
as the dynamics of mixing process of the tracer. A frequency of 40
Hz is achieved which leads to estimation of mixing dynamics with high
time resolution. Validity of the proposed technique is ensured by
comparing mixing time against that determined using a conventional
dye based photographic technique. The proposed technique is thereafter
used to determine mixing time and mixing dynamics under different
operating (needle rotational speed and liquid head) and geometrical
(needle and vessel diameter) conditions.
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